2,6-diamino-1,4-dihydropyridine derivatives

ABSTRACT

2,6-Diamino-1,4-dihydropyridines bearing carbonyl functions in the 3- and 5-positions and being substituted in the 4-position by lower alkyl, phenyl, substituted phenyl or a heterocyclic group are antihypertensive agents and coronary vessel dilators. The compounds, of which 2,6-diamino-4-(3-nitrophenyl)-1,4dihydropyridine-3,5-dicarboxylic acid 3,5-diethyl ester is a representative embodiment, are prepared through condensation of an amidine with either an aldehyde or an ylidenecyanoacetoacetic acid ester.

United States Patent [1 1' Meyer et al.

[ Jan. 14, 1975 I 2,6-DIAMINO-l,4-DIHYDROPYRIDINE DERIVATIVES [76] Inventors: Horst Meyer; Friedrich Bossert;

Wulf Vater, all of Bayer Aktiengesellschaft, Wuppertal-Elberfeld; Kurt Stoepel, In den Birken 69, Wuppertal-Elberfeld, all of Germany [22] Filed: Mar. 27, 1974 [21] App]. No.: 455,257

Related U.S. Application Data [62] Division of Ser. No. 336,483, Feb. 28, 1973.

[30] Foreign Application Priority Data Mar. 6, 1972 Germany 2210687 {52 us. C1 260/295.5 11,260/2564 R,

260/256.4 C, 260/287 R, 260/294.8 D, 260/294.8 F, 260/294.8 G, 260/294.8 R, 260/295.5 B, 260/296 R, 424/251, 424/258, 424/266 Primary ExaminerAlan L. Rotman [57] ABSTRACT 2,6-Diamino-l,4-dihydr0pyridines bearing carbonyl functions in the 3- and 5-positions and being substituted in the 4-position bylower alkyl, phenyl, substi tuted phenyl or a heterocyclic group are antihypertensive agents and coronary vessel dilators The com-- pounds, of which 2,6-diamino-4-(3-nitrophenyl)-1,4--

dihydropyridine-3,S-dicarboxylic acid 3,5-diethyl ester is a representative embodiment, are prepared through condensation of an amidine with either an aldehyde or an ylidenecyanoacetoacetic acid ester.

6 Claims, No Drawings 1 2 2,6-IPIAIYIIlEQ:1 ,4-DIHYDI1OPYRIDINE The term lower alkoxy denotes a straight or branched DERTVA TI VES hydrocarbon chain bound to the remainder of the mol- This is a division of application Ser. No. 336,483 filed ecule through an ethereal oxygen atom as, for example, Feb. 28, 1973. methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobu- 5 toxy, pentoxy and hexoxy.

DETAILED DESCRIPTION The term lower alkylthio denotes a branched or The present invention pertains to 2,6-diamino-1,4- straight hydrocarbon chain bound to the remainder of dihydropyridine derivatives, to process for their prothe molecule through a divalent sulfer as, for example,

duction and use and to pharmaceutical compositions methylthio, ethylthio, propylthio, isopropylthio, hucontaining such compounds and useful as antihyperten- I0 tylthio, and the like.

sive agents and coronary vessel dilators. The term halogen denotes the substituents l'luoro,

In particular, the present invention pertains to comchloro, bromo and iodo.

pounds of the formula: As indicated, the present invention also pertains to H R O the physiologically acceptable non-toxic acid addition 1 ll 2 salts of these basic compounds. Such salts include those R -C C-R derived from organic and inorganic acids such as, withi I out limitation, hydrochloric acid, hydrobromic acid,

, I phosphoric acid, sulfuric acid, methane sulphonic acid,

2 acetic acid, tartaric acid, lactic acid, succinic acid, citric acid, malic acid, maleic acid, sorbic acid, aconitic acid, salicylic acid, phthalic acid, embonic acid, enanthic acid, and the like.

According to the present invention, the foregoing compounds are prepared by reacting an amidine of the formula:

wherein R is hydrogen; lower alkyl; lower alkenyl; lower alky nyl, phenyl; substituted phenyl in which the substituents are one to three members selected from the group consisting of lower alkyl, lower alkoxy, halogeno, nitro, cyano, trifluoromethyl, azido, carbo(lower alkoxy), lower alkylsulfonyl, lower alkylsulfinyl, lower alkylthio H or phenyl; naphthyl; or a heterocyclic ring selected from the group consisting of quinolyl, isoquinolyl, pyri- HZN-C-CHZCOR dyl, pyrimidyl, thenyl, fury! and pyrryl, said heterocyclic ring being unsubstituted or substituted by one or two members selected from the group consisting of lower alkyl, lower alkoxy and halogeno; and

each of R and R taken independently of the other, is lower alkyl, lower alkoxy, lower alkoxy(lower alkoxy), lower alkenyloxy, lower alkynyloxy, amino, lower alkylamino or di(lower alkyl) amino.

wherein R is as herein defined, with either (a) an aldehyde of the formula RCHO wherein R is as herein defined, or (b) with an ylidenecyanoacetic acid derivative of the formula:

The above compounds can be depicted in tautomeric 0 Cl-[R forms, all of which are fully equivalent and fully em- 1 braced by the present invention:

H R CO COR F F th ak of br i y n Convenience, the l in which R and R are as herein defined in the presence dihydro form is employed herein. of an alkali metal alkoxide such sodium 'methoxide. The term lower alkyl denotes a univalent saturated The condensations proceed smoothly in good yields branched or straight hydrocarbon chain containing simply by heating the two components, generally in the from 1 to 6 carbon atoms. Representative of such lower presence of an inert organic solvent such as methanol,

alkyl gr ps are t m hyl. hyl, P PYL P PYL ethanol, propanol and similar alkanols, ethers such as butyl, isobutyl, Sec. butyl, tertutyl. pen yl. i pentyl. dioxane and diethyl ether, glacial acetic acid, pyridine, p y t tp nty yl, a d th li dimethylformamide, dimethylsulfoxide, acetonitrile,

The term lower alkenyl denotes a univalent branched and the like. The reactions are conducted at temperaor straight hydrocarbon chain containing from 2 to 6 6O tures of from 20 to 200C, conveniently at the boiling carbon atoms and nonterminal ethylenic unsaturation i t of the solvent, and while elevated pressure may as, for example, vinyl, allyl, isopropenyl, Z- ut yI, be utilized, normal atmospheric pressure is generally 3-methyl-2-butenyl, 2-pentenyl, 3-pentenyl, 2hexenyl, satisfactory. The reactants are employed in substany and the like, Preferably having 2 t0 4 Carbon tially equimolar amounts when the amidine is reacted atomswith the ylidenecyanoacetic acid whereas at least two The term lower alkynyldenotesaunivalent branched molar equivalents of h idin r m l ed er straight hydrocarbon Chain containing from 2 to 6 molar equivalent of the aldehyde reactant, in which carbon atoms and nonterminal acetylenic unsaturation Case d R are h Same i h dih d idi as, f p y y 'P PY Y 'P and product. The amidine reactant can be employed as the the like Preferably having 2 to 4 Carbon atomsfree base or in the form of a salt such as the hydrohalide salts with the amidine being liberated from the salt I through treatment with a basic agent such as an alkali tonic acid ester to yield a l,4-dihydropyridine (Knoevenagel, Ber. 3l, 743, I898), it would be expected from, for example, Silversmith, J. Org. Chem. 27, 4090 (1952) that the addition of the amidine to the ylideneamidine or the ylidenecyanoacetic acid would yield the dihydropyrimidine derivative rather than the dihydropyridine derivative.

Many of the aldehydes utilized as one of the reactants are known to the art and the others can either be generated in situ as herein described or prepared according to methods well known to the art, see for example Org. Reactions VIII, 218 et seq. (I954). Typical of this reactant are the following compounds:

formaldehyde,

acetaldehyde,

propionaldehyde,

isobutyraldehyde,

cyclopentaldehyde,

cyclohexanaldehyde,

acrolein,

cyclohex-3-enaldehyde,

benzaldehyde,

2-, 3- and 4-methylbenzaldehyde,

2-, 3- and 4-methoxybenzaldehyde,

3,4 and 5-trimethoxybenzaldehyde,

2-isopropoxybenzaldehyde,

2-, 3- and 4-chlorobenzaldehyde,

2-, 3- and 4-bromobenzaldehyde,

2-, 3- and 4-fluorobenzaldehyde,

2,4- and 2,6-dichlorobenzaldehyde,

2,4- and 2,3-dimethylbenzaldehyde,

2-, 3- and 4-nitrobenzaldehyde,

2,6- and 3,5-dinitrobenzaldehyde,

2-nitro-6-bromobenzaldehyde,

Z-nitrol3-methoxy16-chlorobenzaldehyde,

2-nitro-4-chlorobenzaldehyde,

2-nitro-4-methoxybenzaldehyde,

2-, 3- and 4-trifluoromethylbenzaldehyde,

2-carbethoxybenzaldehyde,

3-carbomethoxybenzaldehyde,

4-carbobutoxybenzaldehyde,

3-nitro-4-carbethoxybenzaldehyde-4-carboxylic acid ethyl ester,

a,B-and y-pyridinaldehyde,

6-methylpyridin-Z-aldehyde,

pyrimidin-S-aldehyde,

4,6-dimethoxypyrimidin-5-aldehyde,

2-, 3- and 4-cyanobenzaldehyde,

Z-methylmercaptobenzaldehyde,

4-methylmercaptobenzaldehyde,

2-methylsulphonylbenzaldehyde,

land 2-naphthaldehyde,

5-bromo-I-naphthaldehyde,

Z-ethoxy-l-naphthaldehyde,

4-methyl-I-naphthaldehyde,

quinolin-2-, 3-, 4-, 5-, 6-, 7- and 8-aldehyde,

isoquinolin-l ,3,4-aldehyde, furan-2-aldehyde,

thiophen-2-aldehyde and pyrrol-2-aldehyde.

The ylideneeyanoacetic acid reactants are similarly known or can be readily produced according to known methods, see for example Newman et al., J. Org. Chem., 23, 797 (1958). Typical of these reactants are the following benzylidenecyanoacetic acid methyl ester,

benzylidenecyanoacetic acid ethyl ester,

benzylidenecyanoacetic acid propargyl ester, benzylidenecyanoacetic acid B-methoxyethyl ester, l-naphthylidenecyanoacetic acid ethyl ester, 2-methoxybenzy]idenecyanoacetic acid ethyl ester. 2-methylbenzylidenecyanoacetic acid ethyl ester,

Z-nitrobenzylidenecyanoacetic acid isopropyl ester,

2-trifluoromethylbenzylidenecyanoacetic acid ethyl ester, 2-cyanobenzylidenecyanoacetic acid methyl ester, 2-chlorobenzylidenecyanoacetic acid propyl ester, 4-methylmercaptobenzylidenecyanoacetic acid ethyl ester, a-pyridylmethylidenecyanoacetic acid ethyl ester,

and

Z-furfurylidenecyanoacetic acid ethyl ester.

The amidine reactants are similarly known or can be readily produced according to known methods, see for example McElvain et al., J.A.C. S., 73, 2760 (I951); Typical of these reactants are the following:

amidinoacetic acid methyl ester,

amidinoacetic acid ethyl ester,

amidinoacetic acid n-propyl ester,

amidinoacetic acid isopropyl ester,

amidinoacetic acid cyclohexyl ester,

amidinoacetic acid B-methoxyethyl ester,

amidinoacetic acid a-ethoxyethyl ester,

amidinoacetic acid B-ethoxyethyl ester, amidinoacetic acid propargyl ester, amidinoacetamide, and amidino-N,N-dimethylacetamide.

As noted above, the compounds of the present invention demonstrate the ability to reduce blood pressure and to effect a dilation of the coronary vessels. They can accordingly be used where either or both of these effects are desired. Thus upon parenteral, oral or sublingual administration, the compounds produce a distinct and long lasting dilation of the' coronary vessels which is intensified by a simultaneous nitrite-like effect of reducing the load on the heart. The effect on heart metabolism is thus one of energy saving. In'addition. the compounds lower the blood pressure of normotonie and hypertonic animals and can thus be used as antihypertensive agents; These properties can be conveniently observed in well known laboratory models. Thus for example the coronary vessel dilation effect can be observed by measuring the increase in oxygen saturation in the coronary sinus in the narcotized, heart catheterized dog, as shown in the following table:

nitrophenyl )-l .4- dihydropyridine- 3,5-dicarboxylic acid diethyl ester The hypotensive activity of the present compounds can be observed by measuring the blood pressure of hypertensiv'e rats following administration of the compounds. The followingtable demonstrates the dose which results in at least a mm Hg reduction in blood pressure of such animals:

pyridine-3,S-dicarboxylie acid diethyl CSIBI' 2.6-diamino-4-t 3-nitrophenyl)-l ,4-dihydropyridine-3,S-dicarboxylic acid diethyl ester In addition to the effect on blood pressure and coronary vessels, the compounds also lower the excitability of the stimulus formation and excitation conduction system withinthe heart so that an antifibrillation action is observed at therapeutic doses. The tone of the smooth muscle of the vessels is also greatly reduced. This vascularspasmolytic action can be observed in the entire vascular system as well as in more or less isolated and circumscribed vascular regions such as the central nervous system. In addition, a strong muscularspasmolytic action is manifested in the smooth muscle of the stomach, the intestinal tract, the urogenital tract and the respiratory system. Finally, there is some evidence that the compounds influence the cholesterol level and lipid level ofthe blood. These effects complement one another and the compounds are thus highly desirable as pharmaceutical agents to be used in the treatment of hypertension and conditions characterized by a constriction of the coronary blood vessels.

Pharmaceutical compositions for effecting such treatment will contain a major or minor amount, e.g., from 95 to 0.5 percent, of at least one 2,6-diamino-l ,4- dihydropyridine as herein defined in combination with a pharmaceutical carrier, the carrier comprising one or more solid, semi-solid or liquid diluent, filler and formulation adjuvant which is non-toxic, inert and pharmaceutically acceptable. Such pharmaceutical compositions are preferably in dosage unit form; i.e., physically discrete units containing a predetermined amount of the drug corresponding to a fraction or multiple of the dose which is calculated to produce the desired therapeutic response. The dosage units can contain one, two, three, four or more single doses or, alternatively, one-half, third or fourth ofa single dose. A single dose preferably contains an amount sufficient to produce the desired therapeutic effect upon administration at one application of one or more dosage units according to a predetermined dosage regimen, usually a whole, half, third or quarter of the daily dosage administered once, twice, three or four times a day. Other therapeutic agents can also be present.

Although the dosage and dosage regimen must in each case be carefully adjusted, utilizing sound professional judgment and considering the age, weight and condition of the recipient, the route of administration and the nature and gravity of the illness, generally the daily dose will be from about 0.5 to about 1800 mg/kg, preferably 2.5 to 900 mg/kg, when administered parenterally and from about 25 to about 4500 mg/kg, preferably 50 to 1800 mg/kg, when administered orally. In some instances a sufficient therapeutic effect can be obtained at lower doses while in others, larger doses will be required.

Oral administration can be effected utilizing solid and liquid dosage unit forms such as powders, tablets,'-

dragees, capsules, granulates, suspensions, solution, and the like.

Powders are prepared by comminuting the compound to a suitable fine size and mixing with a similarly comminuted pharmaceutical carrier such as an edible carbohydrate as for example starch, lactose, sucrose, glucose or mannitol. Sweetening, flavoring, preservative, dispersing and coloring agents can also be present.

Capsules are made by preparing a powder mixture as described above and filling formed gelatin sheaths. Glidants and lubricants such as colloidal silica, tale, magnesium stearate, calcium stearate or solid polyethylene glycol can be added to the powder mixture before the filling operation. A disintegrating or solubilizing agent such as agar-agar, calcium carbonate or sodium carbonate can also be added to improve the availability of the medicament when the capsule is ingested.

Tablets are formulated for example by preparing a powder mixture, granulating or slugging, adding a lubricantand disintegrant and pressing into tablets. A powder mixture is prepared by mixing the compound, suitably comminuted, with a diluent or base as described above, and optionally with a binder such as carboxymethyl cellulose, an alginate, gelatin, or polyvinyl pyrrolidone, a solution retardant such as paraffin, a resorption accelerator such as a quaternary salt and/or an absorption agent such as bentonite, kaolin or dicalcium phosphate. The powder mixture can be granulated by wetting with a binder such as syrup, starch paste. acacia mucilage or solutions of cellulosic or polymeric materials and forcing through a screen. As an alternative to granulating, the powder mixture can be run through the tablet machine and the resulting imperfectly formed slugs broken into granules. The granules can be lubricated to prevent sticking to the tablet forming dies by means of the addition of stearic acid, a stcarate salt, talc or mineral oil. The lubricated mixture is then compressed into tablets. The medicaments can also be combined with free flowing inert carriers and compressed into tablets directly without going through the granulating or slugging steps. A clear or opaque protective coating consisting of a sealing coat of shellac, a coating holic vehicle. Suspensions can be formulated by dispersing the compound in a non-toxic vehicle. Solubilizers and emulsifiers such ethoxylated isostearyl alcohols and polyoxyethylene sorbitol esters, preservatives, flavor additives such as peppermint oil or saccharin, and the like can also be added.

Where appropriate, dosage unit formulations for oral administration can be microencapsulated. The formulation can also be prepared to prolong or sustain the release as for example by coating or embedding particulate material in polymers, wax, or the like.

Parenteral administration can be effected utilizing liquid dosage unit forms such as sterile solutions and suspensions intended for subcutaneous, intramuscular or intravenous injection. These are prepared by suspending or dissolving a measured amount of the compound in a non-toxic liquid vehicle suitable for injection such as an aqueous or oleaginous medium and sterilizing the suspension or solution. Alternatively a measured amount of the compound is placed in a vial and the vial and its contents are sterilized and sealed. An accompanying vial or vehicle can be provided for mixing prior to administration. Non-toxic salts and salt solutions can be added to render the injection isotonic. Stabilizers, preservatives and emulsifiers can also be added.

The following examples will serve to further typify the nature of the present invention through the presentation of specific embodiments. These examples should not be construed as a limitation on the scope of the invention since the subject matter regarded as the invention is set forth in-the appended claims.

EXAMPLE 1 H, 00c cooca,

N a, N H NH,

EXAMPLE 2 l H2 N g NH2 Upon boiling a solution of 7.6 g 2-nitrobenzaldehyde and 13.0 g amidinoacetic acid ethyl ester in 150 ml ethanol for two hours, 2,6-diamino-4-(2-nitrophenyl-l,4-

dihydropyridine-3,5-dicarboxylic acid diethyl ester of m.p. 142C (ethanol) is obtained. Yield: 56 percent of theory.

EXAMPLE 3 Upon boiling a solution of 15.1 g 3- nitrobenzaldehyde and 26.0 g amidinoacetic acid ethyl ester in 250 ml ethanol for two hours, 2,6-diamino-4 (3-nitrophenyl )-l ,4-dihydropyridine-3,S-dicarboxylic acid diethyl ester ofm.p. l 176C (ethanol) is obtained.

Yield: 63 percent of theory.

cyanobenzaldehyde and 13.0 g amidinoacetic acid ethyl ester in ml ethanol for two hours, 2,6- diamino-4-(3-cyanophenyl)-l,4-dihydropyridinc-3,5- dicarboxylic acid diethyl ester of m.p. l76C (isopropanol) is obtained.

Yield: 55 percent of theory.

EXAMPLE 5 H H 'C OOC COOC H, l l r N H N H NH Upon boiling a solution of 6.0 g 2- methylbenzaldehyde and 13.0 g amidinoacetic acid ethyl ester in 150 ml ethanol for two hours, 2,6- diamino-4-( 2-methylphenyl )-l .4-dihydropyridine-3 .5- dicarboxylic acid diethyl ester of m.p. 158C (ethanol) is obtained.

Yield: 67 percent of theory.

EXAMPLE6 CH, H H,C OOC I l COOC H H N g mt Upon boiling a soluton of 6.8 g 2- methoxybenzaldehyde and 13.0 g amidinoacetic acid ethyl ester in 150 ml ethanol for two hours, 2,6-

9 diamino-4-(2-methoxyphenyl)-1 ,4-dihydropyridine- 3,5-dicarboxylic acid diethyl ester ofmp. 147C (ethanol) is obtained.

Yield: 72 percent of theory.

fluorobenzaldehyde and. 13.0 g amidinoacetic acid ethyl ester in 150 ml ethanol for one hour, 2,6-diamino- 4-(2-t'luorophenyl)-1,4-dihydropyridine-3,5- dicarboxylic acid diethyl ester of m.p. 128 130C (ethanol) is obtained.

Yield: 49 percent of theory.

EXAMPLES a,c ooc I I cooc a, H2N g NH:

Upon boiling a solution of 8.7 g 2-trifluoromethylbenzaldehyde and 13.0 g amidinoacetic acid ethyl ester in 150 ml of ethanol for two hours, 2,6-diamino-4-(2- trifluoromethylphenyl)-1,4dihydropyridine-3,5- dicarboxylic acid diethyl ester of m.p. 191C (ethanol) is obtained.

Yield: 70 percent of theory.

EXAMPLE9 a,c ooc I cooc a,

l H N g NHz Upon heating a solution of 8.7 g 3-trifluorome thylbenzaldehyde and 13.0 g amidinoacetic acid ethyl ester in 150 ml ethanol for one hour, 2,6-diamino-4-(3- trifluoromethylphenyU-l ,4-dihydropyridine-3,5- dicarboxylic acid diethyl ester fm.p. 170C (isopropan01) is obtained.

Yield: 56 percent of theory.

EXAMPLE 10 H s a,c,ooc cooc n,

H211 g Na,

Upon boiling a solution of 5.0 g aeetaldehydeand 260g amidinoacetic acid ethyl ester in 150 ml ethanol for two hours, 2,6-diamino-4methyl-l ,4- dihydropyridine-3,5-dicarboxylic acid diethyl ester of m.p. 136C (ethyl acetate/petroleum ether) is obtained. Yield: 61 percent of theory.

EXAMPLEll N0 c \l H rgc ooc I cooe n HZN H Na Upon boilinga solution of 9.3 g 3-nitro-6- ehlorobenzaldehyde and 13.0 g amidinoacetic acid ethyl ester in 150 ml ethanol for two hours, 2,6- diamino-4-(3-nitro-6-chlorophenyl)-1-,4 dihydropyridine-3,S-dicarboxylic.acid diet'hyl ester 01 m.p. C (ethanol) is obtained.

Yield: 48 percent of theory.

EXAMPLE 12 I Upon heating a solution of 5.4 g a-pyridinaldehyde and 13.0 g amidinoacetic acid ethyl ester in ml ethanol for two hours, 2,6-diamino-4-(a-pyridyl)-1,4- dihydropyridine-3,5-dicarboxylic acid diethyl ester of m.p. C (ethanol) is obtained.

Yield: 74 percent of theory.

. EXAMPLE l3 Upon heating a solution of 8.4 g 4,6- dimethoxypyrimidine-5-aldehyde and 13.0. g amidinoaceticacid ethyl ester in 150 ml ethanol for two hours,

2,6-diamino-4-(4,6-dimethoxypyrimid-5-yl )-l ,4-

1 1 dihydropyridine-3,5-dicarboxylic acid diethyl ester of m.p. 219C (ethanol) is obtained.

Yield: 56 percent of theory.

EXAMPLE 14 Upon boiling a solution of 4.8 g furan-2-aldehyde and 15 13.0 g amidinoacetic acid ethyl ester in 150 ml ethanol for two hours, 2,6-diamino-4-(furyl-2)-1,4- dihydropyridine-3,5-dicarboxylic acid diethyl ester of m.p. 147 148C (ethanol) is obtained.

Yield: 74 percent of theory.

EXAMPLE 15 H,C O0C I I COOC H, N

Upon boiling a solution of 7.8 g l-naphthaldehyde Upon heating a solution of 7.8 g quino1ine-4- aldehyde and 13.0 g amidinoacetic acid ethyl ester in 200 ml ethanol for two hours, 2,6-diamino-4-(quinol-4- yl)-1,4-dihydropyridine-3,S-dicarboxylic acid diethyl ester of m.p. 145 (ethanol) is obtained.

Yield: 58 percent of theory.

EXAMPLE 17 60 son,

Upon heating a solution of 7.6 g 4-methylmercaptobenzaldehyde and 13.0 g amidinoacetic acid ethyl ester in 200 ml ethanol for two hours, 2,6-diamino-4- (4-methylmercaptophenyl)1,4-dihyropyridine-3.5- dicarboxylic acid diethyl ester of m.p. 127C (isopropunol) is obtained. Yield: 48 percent of theory.

EXAMPLE 18 H 11,0 00 1 I coocgr, H, N 5 NH,

Upon heating a solution of 9.1 g biphenyl-Z-aldehyde and 13.0 g amidinoacetic acid ethyl ester in 200 ml ethanol for two hours. 2,6-diamino-4-(biphenyl-Z-yl)v-l,4 dihydropyridine-3.S-dicarboxylic acid diethyl ester of m.p. 215 (ethanol) is obtained.

Yield: 33 percent of theory.

EXAMPLE 19 H Ho e-cit, 00c cooca c cn HZN H NH,

Upon heating a solution of 7.6 g nitrobenzaldehyde and 14.0 g amidinoacetic acid propargyl ester in 200 ml ethanol for two hours, 2,6-diamino-4-(3-nitrophenyl)- 1,4-dihydropyridine 3.S-dicarboxylic acid dipropargyl ester of m.p. (ethanol) is obtained.

Yield: 59 percent of theory.

EXAMPLE 20 Upon heating a solution of 5.4 g pyridine-4-aldehydc and 14.4 g amidinoacetic acid isopropyl ester in 200ml ethanol, 2,6-diamino-4-(pyrid-4-y1)-l,4- dihydropyridine-3,5dicarhoxylic acid diisopropyl ester of m.p. 263C (ethanol) is obtained.

Yield: 76 percent of theory.

EXAMPLE 21 EXAMPLE 24 cooc H,

11 C COOCH(CH, H v 11, c 000 0000 H, H2 H 2 i i H N N N Upon heating a solution of 10.1 g ben- 2 H zylidenecyanoacetic acid ethyl ester, 7.2 g amidinoacetic acid isopropyl ester and 0.6 g sodium ethylate in Upon boiling a solution of 8.9 g 3-carbethoxyben- 150 ml ethanol for four hours, 2,6-diamino-4-phenylzaldehyde and 13.0 g amidinoacetic acid ethyl ester in l,fl-dihydropyridine-3,S-dicarboxylic acid 3-ethyl ester 100 h l fo two hours, 2 -di i -4 3 p py ester o pobtainedcarbethoxyphenyl)-l ,4-dihydropyridine-3.5- Yleld: 54 percent of theory 15 dicarboxylic acid diethyl ester of mp. 191C (ethanol) EXAMPLE 22 is obtained.

Yield: 32 percent of theory.

What is claimed is: 1. A compound of the formula 2 H,c,ooc cooen(cn,), R B

. 1 2 N R R. N N H H2 25 "2 I N z Upon heating a solution, of 12.3 g 2- H nitrobenzylidenecyanoacetic acid ethyl ester, 7.2 g

amidinoacetic acid isopropyl ester and 0.6 g sodium wherein v ethylate in 150 ml ethanol for four hours, 2,6-diamino-' R P n furyl Pyrryl or thlenyl, unsubsmutcd or 4-(2-nitrophenyl)-l,4-dihydropyridine-3,5- Substituted by one or two members selected from dicarboxylic acid-3-isopropyl ester 5-ethyl ester ofm.p. the group consisting of lower alkyl, lower alkoxy 110C is obtained. and halogeno; and

Yield: 54 percent Of theory. each of R and R taken independently of the other,

EXAMPLE 23 1 is lower alkoxy, lower alkoxy(lower alkoxy), al-

kenyloxy of 2 to 4 carbon atoms, alkynyloxy of 2 to 4 carbon atoms, amino, lower alkylamino or di(- lower alkyl) amino. 2. A compound according to claim 1 wherein R and R are lower alkoxy.

00c I I C0002 5 3. A compound according to claim 1 which is 2,6-

N diamino-4-( a-pyridyl l ,4-dihydropyridine-3,5 z" H dicarboxylic acid diethyl ester.

4. A compound according to claim 1 which is 2,6 diamino-4-(furyl-2)-1,4-dihydropyridine3,5-

p heating a Solution of 7.3 g dicarboxylic acid diethyl ester.

azidobenzaldehyde and 13.0 g amidinoacetic acid ethyl compwlld according to wh'ch ester in 150 ml ethanol for two hours, 2,6-diamino-4- P i4'dlhydmpyrldmc'35' (2-azidophenyl)-1,4-dihydropyridine-3,S-dicarboxylic dlcarbox-yhc acld p py ester acid diethyl ester of mp. 250C (ethanol) is obtained. 6- A Compound according to claim 1 wherein R is Yield: 46 percent of theory. pyridyl or furyl.

9 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 86O,6Ol Dated January 14, 1.975

' Inventor(s) HORST MEYER; FREIDRICH BOSSERT; WULF VA'IER It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 14, line 31, between "furyl" and "pyrryl" insert a Signed and Sealed this D Twenty-seventh Day Of July 1976 [SEAL] Arrest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner uj'Parents and Tradomurkx UNITED V STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,860,601 Dated January 14; 1975 Inventor(s) Horst Meyer; Friedrich Bossert Wulf Vater It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

comm 1, line 15, the number of the German priority document should be P 2210687.2

Insert the assignee Bayer Ak'tiengesellschaft, Deverkusen, Germany Signed and sealed this 1st day of April 1975.

Attest:

C. MARSHALL DANN Commissioner of Patents and Trademarks RUTP C. ZIASON Attesting Officer 

2. A compound according to claim 1 wherein R1 and R2 are lower alkoxy.
 3. A compound according to claim 1 which is 2,6-diamino-4-( Alpha -pyridyl)-1,4-dihydropyridine-3,5-dicarboxylic acid diethyl ester.
 4. A compound according to claim 1 which is 2,6-diamino-4-(furyl-2)-1,4-dihydropyridine-3,5-dicarboxylic acid diethyl ester.
 5. A compound according to claim 1 which is 2,6-diamino-4-(pyrid-4-yl)-1,4-dihydropyridine-3,5-dicarboxylic acid diisopropyl ester.
 6. A compound according to claim 1 wherein R is pyridyl or furyl. 